Overview - Phaseo Docs

Use the TypeScript Agent SDK when your app needs more than one-shot generation:

multi-step local tool loops
resumable run state
gateway-backed model turns
validated structured outputs, streamed progress, and plugin-aware routing

It builds on top of @phaseo/sdk and defines the reference runtime contract shared by the other Agent SDK languages.

Runtime capability matrix

Capability	SDK support
Executable and concurrent tools	Built in, with deterministic result ordering and per-tool timeouts
Runtime validation	Input, output, event, and final agent schemas through `parse`, `safeParse`, or validator functions
Human approval	Per-tool or per-call approval with exact call-ID approval and rejection on resume
Human-in-the-loop tools	`onToolCalled` pause and `onResponseReceived` transformation
Manual tools	`execute: false` plus externally supplied `toolOutputs`
Progress-producing tools	Async-generator tools and `tool.preliminary_result` events
Tool error recovery	Fail the run or return a structured tool error to the model
Streaming	Model deltas plus replayable text, reasoning, item, tool, and full event consumers
Stop controls	Steps, duration, tokens, cost, tool call, finish reason, and custom predicates
Dynamic turns	Dynamic model, instructions, sampling values, tool sets, context mutation, and `nextTurnParams`
Durable continuation	Serializable run results or an application-owned `state` load/save accessor
Observability	Normalized usage and cost, warnings, finish reasons, step results, lifecycle events, and local devtools

What you get

createAgent()
defineTool()
createGatewayAgentClient()
run(), stream(), continueRun(), and continueStream()
executable, manual, approval-gated, and human-in-the-loop tools
runtime input/output schemas, generator progress, composable stop conditions, and usage/cost summaries
optional application-owned state accessors and lifecycle events for devtools

Next

Last modified on July 26, 2026